This application represents a request for continued funding of a clinical trial developed and initiated during the first 5 years of our SCOR program. This study is currently funded as an interdependent R0-1 (DK-42892). Upon funding of our SCOR competitive renewal, we intend to terminate the R01. We feel that the inter-relationships of the projects and their reliance on each other justifies this approach. In addition, the clinical trial will require significant support from the Cores supporting the SCOR. Thus it seems natural to include this study, conducted thereby in a more cost effective fashion, as part of our SCOR renewal application. In Project 5 of our original application, we proposed a series of studies to determine if bone loss can be modified in patients with established osteoporosis, basing our research plans on data already gathered by our group, or data that were to be generated in the other SCOR projects. Our major goal was to develop a novel approach to the treatment of patients with Type I osteoporosis. The broad concepts of the treatment protocol proposed were, at that time, based on our observations that short term administration of phosphate (PO4) might activate bone remodeling by creating a secondary hyperparathyroidism. In initial studies we compared the response of the PTH/vitamin D system to phosphate and to (1-34)hPTH administration. As a result of the data collected, it became evident that using PO4 as an indirect stimulus to skeletal remodeling would be less than effective. In our original application we declared our intent to use (1- 34)HPTH when it became available for use as a therapeutic agent. Since (1- 34)HPTH was made available to us by Rhone Poulenc Rorer in 1989, we pursued the intended alternative strategy to evaluate the use of (1-34)hPTH directly in a treatment protocol similar to that in our original SCOR, but eliminating the use of PO4.